NUS Engineering is kicking off its latest research initiative, Hybrid-Integrated Flexible Electronic Systems, with innovative projects that integrate different types of electronics into complex systems that are flexible and high-performing, to enhance and expand the application of flexible technologies.

Three NUS Engineering projects currently in progress include a flexible high performance terahertz light emitter; an insole that measures foot pressure for diabetics using flexible sensing technologies; and flexible electronic skin for use in advanced robotics and prosthetics.

Terahertz light — with wavelengths between that of infrared light and microwave light — is commonly used for sensing and imaging, such as in security to detect hidden objects, as well as in medical diagnostics to detect cancer cells. Commercial terahertz emitting systems are large, rigid and very costly. In response to this, a low-cost, flexible terahertz light emitter was developed in a project led by Associate Professor Yang Hyunsoo from NUS Electrical and Computer Engineering and NUS Nanoscience and Nanotechnology Institute. The device is comprised of very thin layers of tungsten and cobalt — measured in the nanometres, and can be powered by low cost fibre lasers. The team hopes to eventually use this flexible emitter in a system for real-time cancer cell sensing.

Diabetics regularly experience numbness in their feet, and this makes it difficult for them to sense pain if they develop foot ulcer, which can be a common complication. It is thus important to track the pressure on their feet. A team led by Professor Lim Chwee Teck from NUS Biomedical Engineering has developed an insole with microfluidic sensors that monitors pressure in real-time. A microfluidic channel filled with a liquid metal alloy is used as a sensor. Pressure placed on these sensors by feet will displace the liquid, changing the electric resistance and allowing the forces on different parts of the foot to be measured. The data can then be sent to an app on a mobile phone that can be monitored by both the patient and the physician. This technology is being commercialised by Flexosense, a NUS start-up.

Prof Thakor (far right) and lead of the research on the electronic skin, Dr Sunil Kukreja (far left), and their team with the electronic skin enhanced prosthetic arm

Controlling how prosthetic hands grasp objects is a challenge faced by amputees that is still difficult to overcome. The Singapore Institute for Neurotechnology (SINAPSE) at NUS, under the leadership of Prof Nitish Thakor, is working to address this gap in prosthesis. They have developed an electronic skin — made of flexible and stretchable semiconductive cloth and embedded with touch sensors — that enables the prosthetic to sense and differentiate types of touch, and determine the strength of grasp to use. The prosthesis is also enhanced by vision sensors that automatically determine the grasp type and orientation the hand should take on.